That depends on our program goals. Here are some possibilities:
1. Be the Biggest - we had our heyday on this one (back in '96), and have since fallen behind the leaders (Michigan, Penn State, A&M, Ohio State). Don't know if there's a path to get back to the top even if that were our goal, but chairbacks certainly wouldn't help.
2. Best Fan Experience - chairbacks would be super-nice for everyone upgrading from bench seats.
3. Home Crowd Advantage - on the face of it, reduced attendance would seem to hurt crowd noise. But noise is a complicated thing, would have to do some modelling...it is possible (not likely, but possible) that 80,000 sound-energy-generators (you and me), well placed, could focus sound better onto the field than 102,455 where the sound waves cancel each other somewhat. I mean, Arrowhead Stadium is objectively the loudest venue in the US, at 142 decibels...with just 76k seating. So it's complicated. Call this one an unknown, but leaning toward it doesn't help.
4. Shift focus to TV audience - it is already true that TV viewers outnumber in-person viewers significantly. Like, maybe as much as 50 to 1. The 2019 Vols-UGa game had 5.77m viewers; that's 56 folks watching through a flat screen for every butt in a seat at Neyland, even if Neyland were filled to capacity (it wasn't). So some might say that the in-house crowd is just window dressing, of sorts, that the real audience for the game is watching via (almost always) ESPN-owned broadcasting. Chairbacks would be absolutely fine, here.
See what I mean? The answer really does depend on your objective. I personally am a huge fan of #3, the hometown advantage the stadium and we give our lads. I just don't know if we hurt it significantly by adding chairback seating. I don't mind us not pushing for #1 any more, especially since we can always agree to another Battle at Bristol if the record for attendance ever seems to be under attack. Having a "mega-stadium" nearby certainly does ease this pressure, hehe.
All in all, for me, I think adding chairbacks would not be such a bad thing, IF we can get some sound engineers to figure out ways to make 80,000 in the future sound like 102,455 do today.